fix: wrong scroll position when switching DMs (RocketChat#36662)

Author: MartinSchoeler

.changeset/strange-stingrays-live.md

@@ -0,0 +1,5 @@
+---
+"@rocket.chat/meteor": patch
+---
+
+Fixes scroll issue when moving between channels or DMs

apps/meteor/client/views/room/body/hooks/useRestoreScrollPosition.spec.tsx

@@ -36,6 +36,30 @@ describe('useRestoreScrollPosition', () => {
 		expect(screen.getByTestId('scrollable-element')).toHaveProperty('scrollTop', 123);
 	});
 
+	it('should jump to bottom if atBottom is true', () => {
+		const store = {
+			scroll: 123,
+			atBottom: true,
+			update: jest.fn(),
+		};
+		(RoomManager.getStore as jest.Mock).mockReturnValue(store);
+
+		const Test = () => {
+			const { innerRef } = useRestoreScrollPosition('GENERAL');
+			return (
+				<div ref={innerRef} style={{ height: '100px', overflowY: 'scroll' }} data-testid='scrollable-element'>
+					<div style={{ height: '800px' }}></div>
+				</div>
+			);
+		};
+
+		render(<Test />);
+
+		expect(screen.getByTestId('scrollable-element')).toBeInTheDocument();
+		expect(screen.getByTestId('scrollable-element')).toHaveStyle({ height: '100px', overflowY: 'scroll' });
+		expect(screen.getByTestId('scrollable-element')).toHaveProperty('scrollTop', 0);
+	});
+
 	it('should do nothing if no previous scroll position is stored', () => {
 		const store = {
 			scroll: undefined,

apps/meteor/client/views/room/body/hooks/useRestoreScrollPosition.ts

@@ -14,6 +14,10 @@ export function useRestoreScrollPosition(rid: string, wait = 100) {
 					return;
 				}
 				const store = RoomManager.getStore(rid);
+				if (store?.atBottom) {
+					node.scrollTop = node.scrollHeight;
+					node.scrollLeft = 30;
+				}
 				if (!jumpToRef.current && store?.scroll !== undefined && !store.atBottom) {
 					node.scrollTop = store.scroll;
 					node.scrollLeft = 30;